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[official-gcc.git] / gcc / value-relation.h
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1 /* Header file for the value range relational processing.
2 Copyright (C) 2020-2021 Free Software Foundation, Inc.
3 Contributed by Andrew MacLeod <amacleod@redhat.com>
5 This file is part of GCC.
7 GCC is free software; you can redistribute it and/or modify it under
8 the terms of the GNU General Public License as published by the Free
9 Software Foundation; either version 3, or (at your option) any later
10 version.
12 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
13 WARRANTY; without even the implied warranty of MERCHANTABILITY or
14 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
15 for more details.
17 You should have received a copy of the GNU General Public License
18 along with GCC; see the file COPYING3. If not see
19 <http://www.gnu.org/licenses/>. */
21 #ifndef GCC_VALUE_RELATION_H
22 #define GCC_VALUE_RELATION_H
25 // This file provides access to a relation oracle which can be used to
26 // maintain and query relations and equivalences between SSA_NAMES.
28 // The general range_query object provided in value-query.h provides
29 // access to an oracle, if one is available, via the oracle() method.
30 // Thre are also a couple of access routines provided, which even if there is
31 // no oracle, will return the default VREL_NONE no relation.
33 // Typically, when a ranger object is active, there will be an oracle, and
34 // any information available can be directly queried. Ranger also sets and
35 // utilizes the relation information to enhance it's range calculations, this
36 // is totally transparent to the client, and they are free to make queries.
39 // relation_kind is a typedef of enum tree_code, but has restricted range
40 // and a couple of extra values.
42 // A query is made requesting the relation between SSA1 and SSA@ in a basic
43 // block, or on an edge, the possible return values are:
45 // EQ_EXPR, NE_EXPR, LT_EXPR, LE_EXPR, GT_EXPR, and GE_EXPR mean the same.
46 // VREL_NONE : No relation between the 2 names.
47 // VREL_EMPTY : Impossible relation (ie, A < B && A > B produces VREL_EMPTY.
49 // The oracle maintains EQ_EXPR relations with equivalency sets, so if a
50 // relation comes back EQ_EXPR, it is also possible to query the set of
51 // equivlaencies. These are basically bitmaps over ssa_names.
53 // relations are maintained via the dominace trees, are are optimized assuming
54 // they are registered in dominance order. When a new relation is added, it
55 // is intersected with whatever existing relation exists in the dominance tree
56 // and registered at the specified block.
59 // Rather than introduce a new enumerated type for relations, we can use the
60 // existing tree_codes for relations, plus add a couple of #defines for
61 // the other cases. These codes are arranged such that VREL_NONE is the first
62 // code, and all the rest are contiguous.
64 typedef enum tree_code relation_kind;
66 #define VREL_NONE TRUTH_NOT_EXPR
67 #define VREL_EMPTY LTGT_EXPR
69 // General relation kind transformations.
70 relation_kind relation_union (relation_kind r1, relation_kind r2);
71 relation_kind relation_intersect (relation_kind r1, relation_kind r2);
72 relation_kind relation_negate (relation_kind r);
73 relation_kind relation_swap (relation_kind r);
74 void print_relation (FILE *f, relation_kind rel);
77 class relation_oracle
79 public:
80 virtual ~relation_oracle () { }
81 // register a relation between 2 ssa names at a stmt.
82 void register_stmt (gimple *, relation_kind, tree, tree);
83 // register a relation between 2 ssa names on an edge.
84 void register_edge (edge, relation_kind, tree, tree);
86 // Return equivalency set for an SSA name in a basic block.
87 virtual const_bitmap equiv_set (tree, basic_block) = 0;
88 // register a relation between 2 ssa names in a basic block.
89 virtual void register_relation (basic_block, relation_kind, tree, tree) = 0;
90 // Query for a relation between two ssa names in a basic block.
91 virtual relation_kind query_relation (basic_block, tree, tree) = 0;
92 // Query for a relation between two equivalency stes in a basic block.
93 virtual relation_kind query_relation (basic_block, const_bitmap,
94 const_bitmap) = 0;
96 virtual void dump (FILE *, basic_block) const = 0;
97 virtual void dump (FILE *) const = 0;
98 void debug () const;
101 // This class represents an equivalency set, and contains a link to the next
102 // one in the list to be searched.
104 class equiv_chain
106 public:
107 bitmap m_names; // ssa-names in equiv set.
108 basic_block m_bb; // Block this belongs to
109 equiv_chain *m_next; // Next in block list.
110 void dump (FILE *f) const; // Show names in this list.
111 equiv_chain *find (unsigned ssa);
114 // The equivalency oracle maintains equivalencies using the dominator tree.
115 // Equivalencies apply to an entire basic block. Equivalencies on edges
116 // can be represented only on edges whose destination is a single-pred block,
117 // and the equivalence is simply applied to that succesor block.
119 class equiv_oracle : public relation_oracle
121 public:
122 equiv_oracle ();
123 ~equiv_oracle ();
125 const_bitmap equiv_set (tree ssa, basic_block bb);
126 void register_relation (basic_block bb, relation_kind k, tree ssa1,
127 tree ssa2);
129 relation_kind query_relation (basic_block, tree, tree);
130 relation_kind query_relation (basic_block, const_bitmap, const_bitmap);
131 void dump (FILE *f, basic_block bb) const;
132 void dump (FILE *f) const;
134 protected:
135 bitmap_obstack m_bitmaps;
136 struct obstack m_chain_obstack;
137 private:
138 bitmap m_equiv_set; // Index by ssa-name. true if an equivalence exists.
139 vec <equiv_chain *> m_equiv; // Index by BB. list of equivalences.
140 vec <bitmap> m_self_equiv; // Index by ssa-name, self equivalency set.
142 void limit_check (basic_block bb = NULL);
143 equiv_chain *find_equiv_block (unsigned ssa, int bb) const;
144 equiv_chain *find_equiv_dom (tree name, basic_block bb) const;
146 bitmap register_equiv (basic_block bb, unsigned v, equiv_chain *equiv_1);
147 bitmap register_equiv (basic_block bb, equiv_chain *equiv_1,
148 equiv_chain *equiv_2);
149 void register_initial_def (tree ssa);
150 void add_equiv_to_block (basic_block bb, bitmap equiv);
153 // Summary block header for relations.
155 class relation_chain_head
157 public:
158 bitmap m_names; // ssa_names with relations in this block.
159 class relation_chain *m_head; // List of relations in block.
160 relation_kind find_relation (const_bitmap b1, const_bitmap b2) const;
163 // A relation oracle maintains a set of relations between ssa_names using the
164 // dominator tree structures. Equivalencies are considered a subset of
165 // a general relation and maintained by an equivalence oracle by transparently
166 // passing any EQ_EXPR relations to it.
167 // Relations are handled at the basic block level. All relations apply to
168 // an entire block, and are thus kept in a summary index by block.
169 // Similar to the equivalence oracle, edges are handled by applying the
170 // relation to the destination block of the edge, but ONLY if that block
171 // has a single successor. For now.
173 class dom_oracle : public equiv_oracle
175 public:
176 dom_oracle ();
177 ~dom_oracle ();
179 void register_relation (basic_block bb, relation_kind k, tree op1, tree op2);
181 relation_kind query_relation (basic_block bb, tree ssa1, tree ssa2);
182 relation_kind query_relation (basic_block bb, const_bitmap b1,
183 const_bitmap b2);
185 void dump (FILE *f, basic_block bb) const;
186 void dump (FILE *f) const;
187 private:
188 bitmap m_tmp, m_tmp2;
189 bitmap m_relation_set; // Index by ssa-name. True if a relation exists
190 vec <relation_chain_head> m_relations; // Index by BB, list of relations.
191 relation_kind find_relation_block (unsigned bb, const_bitmap b1,
192 const_bitmap b2) const;
193 relation_kind find_relation_block (int bb, unsigned v1, unsigned v2,
194 relation_chain **obj = NULL) const;
195 relation_kind find_relation_dom (basic_block bb, unsigned v1, unsigned v2) const;
196 relation_chain *set_one_relation (basic_block bb, relation_kind k, tree op1,
197 tree op2);
198 void register_transitives (basic_block, const class value_relation &);
202 // A path_oracle implements relations in a list. The only sense of ordering
203 // is the latest registered relation is the first found during a search.
204 // It can be constructed with an optional "root" oracle which will be used
205 // to look up any relations not found in the list.
206 // This allows the client to walk paths starting at some block and register
207 // and query relations along that path, ignoring other edges.
209 // For registering a relation, a query if made of the root oracle if there is
210 // any known relationship at block BB, and it is combined with this new
211 // relation and entered in the list.
213 // Queries are resolved by looking first in the list, and only if nothing is
214 // found is the root oracle queried at block BB.
216 // reset_path is used to clear all locally registered paths to initial state.
218 class path_oracle : public relation_oracle
220 public:
221 path_oracle (relation_oracle *oracle = NULL);
222 ~path_oracle ();
223 const_bitmap equiv_set (tree, basic_block);
224 void register_relation (basic_block, relation_kind, tree, tree);
225 void killing_def (tree);
226 relation_kind query_relation (basic_block, tree, tree);
227 relation_kind query_relation (basic_block, const_bitmap, const_bitmap);
228 void reset_path ();
229 void dump (FILE *, basic_block) const;
230 void dump (FILE *) const;
231 private:
232 void register_equiv (basic_block bb, tree ssa1, tree ssa2);
233 equiv_chain m_equiv;
234 relation_chain_head m_relations;
235 relation_oracle *m_root;
236 bitmap m_killed_defs;
238 bitmap_obstack m_bitmaps;
239 struct obstack m_chain_obstack;
241 #endif /* GCC_VALUE_RELATION_H */